This invention relates to a device for use in threading webs of paper or the like along prescribed paths through a rotary printing press preparatory to printing thereon. More particularly, the invention deals with such a device to be installed at an intersection of two or more crossing web guideways, or at a junction of four or more radially converging web guideways, for variously switching a web from one such guideway to another during web threading.
The web-fed rotary printing press has been used extensively, as for newspaper production, in which a plurality of webs of paper are fed from separate rolls into and through separate printing units, to a folding station. The paths of the webs have become more and more involved in recent years as the trend has been, and no doubt will continue to be, toward more colors and more pages. Particularly along the paths from the printing to the folding stations, numerous guide rollers and turnbars congregate, causing the webs to converge, diverge, and turn one way or the other many times.
A variety of devices have been suggested and used for threading webs, as they are paid out from their rolls at the supply stations of the press, along preselected ones of several alternative threading guideways extending along all the possible paths to be traced by the webs. The threading guideways include points where one guideway ramifies into two or more, where two or more guideways merge into one, and where two or more guideways intersect. Special threading guides of different constructions, with or without a switching function, have been used at such points to suit the specific requirements of these points.
Japanese Patent Publication No. 6-88695 indicate several such threading guides for use at intersections or junctions of threading guideways. Installed at a point of divergence of one threading guideway into three, one such threading guide has a movable switch having defined therein three separate switching guideways for communicating the one upstream guideway with a desired one of the three downstream guideways. Two fluid-actuated cylinders in tandem arrangement are coupled to the switch for linearly moving the same to any of the three different positions required for guiding the web from the upstream guideway into any of the three downstream ones.
Another threading guide according to the same Japanese patent publication is immovably mounted at an intersection of two intersecting threading guideways. The threading guide itself has defined therein two intersecting guideways in constant communication with the two threading guideways.
Still another such threading guide according to the above Japanese patent publication is intended for use at a point where three threading guideways converge into one. The converging guide has defined therein three guideways which are open to the three upstream guideways and which converge into one that is open to the downstream guideway.
In order to assess these prior art threading guides, there may be considered a set of alternative web paths defined by four guide rollers that are arranged, so to say, at the corners of a notional square or rectangle as seen in an end view. The second recited threading guide, with the two intersecting guideways, was conventionally mounted at the center of the four guide rollers, also as seen in an end view, for guiding the two possible webs to be threaded between the two diagonally opposite pairs of guide rollers, each pair consisting of one predetermined upstream and one predetermined downstream roller. Further, since webs may be threaded parallel to each other from the two upstream to the two downstream guide rollers, two divergent threading guides set forth above, each with a movable switch, had to be mounted adjacent the upstream guide rollers, and two convergent threading guides adjacent the downstream guide rollers, respectively.
Put to use in a rotary printing press equipped for automatic web threading in particular, these prior art devices cumbersomely crowded the neighborhoods of the guide rollers in question. In some instances, indeed, they necessitated the printing press itself to be redesigned and rendered larger in size, with the guide rollers spaced wider apart from each other and from any neighboring parts.
A more advanced, multiway switching device, capable of single-handedly performing all the functions of the noted three or more conventional devices, is taught by Japanese Patent No. 2,521,385. It comprises a pair of rotary switching disks having several switching guideways cut in a prescribed pattern therein for guiding the pair of lateral edges of the web being threaded. Each switching disk is to be rotatably mounted at a junction of four web-threading guideways of radial arrangement, with a constant angular spacing of ninety degrees about the axis of rotation of the disk.
The switching guideways in each disk include one rectilinear guideway extending diametrally of the disk for intercommunicating any two of the four web-threading guideways that are opposed to each other across the disk, and four arcuate guideways arranged symmetrically on both sides of the rectilinear guideway each for intercommunicating two web-threading guideways neighboring circumferentially of the disk. All the four arcuate switching guideways in the disk are slightly out of alignment with the four web-threading guideways when the single rectilinear switching guideway is positioned in alignment with either one diametrally opposed pair of web-threading guideways. However, when any two circumferentially neighboring web-threading guideways are in alignment with any one of the four arcuate switching guideways in the disk, so are the other two circumferentially neighboring web-threading guideways with one of the other three arcuate switching guideways.
An objection to this prior art multiway switching device is that each switching disk had to be swiveled different angles depending upon how the web-threading guideways are switched. Let it be supposed for example that the switching disk has been positioned with the rectilinear switching guideway in alignment with either one diametrally opposed pair of web-threading guideways. The disk will have to be turned ninety degrees from that angular position for intercommunicating the other diametrally opposed pair of web-threading guideways, and a much less angle in either direction for intercommunicating the web-threading guideways in desired circumferentially neighboring pairs.
Thus the prior art multiway switching device demanded an actuator mechanism that is capable of both revolving the disks ninety degrees and bidirectionally turning the same a much smaller angle. Such an actuator mechanism is of course far more complex and expensive in construction than if the switching disks need to be turned one fixed angle only for performing the multiple switching functions.
The present invention seeks to provide an improved multiway switching device of the general character defined, so made that it requires a switch actuating mechanism of materially simpler and less expensive construction than that of the closest prior art.
Briefly, the invention may be summarized as a multiway switching device for installation at a junction of a plurality of web-threading guideways in a rotary printing press for selectively switching a web from one to another of the guideways. The switching device comprises a rotary switch to be rotatably mounted to frame means at a junction of a plurality of web-threading guideways, which are of substantially radial arrangement about an axis of rotation of the rotary switch. The rotary switch has defined therein two intersecting switching guideways each for intercommunicating one pair of the web-threading guideways which are opposed to each other across the rotary switch, and at least one additional switching guideway for intercommunicating preselected two of the web-threading guideways which are adjacent each other peripherally of the rotary switch. Also included are switch drive means for causing angular displacement of the rotary switch relative to the frame means between a position where the two opposed pairs of web-threading guideways are intercommunicated via the two intersecting switching guideways, and at least one other position where the preselected two neighboring ones of the web-threading guideways are intercommunicated via the additional switching guideway.
Typically, the rotary switch is mounted at a junction of four web-threading guideways having a constant angular spacing of 45 degrees. For switching these four web-threading guideways, the rotary switch has two orthogonally intersecting, rectilinear switching guideways, and two arcuate switching guideways of symmetrical arrangement with respect to one of the rectilinear switching guideways. Each rectilinear switching guideways intercommunicates one pair of web-threading guideways that are opposed to each other diametrally of the rotary switch. Each arcuate switching guideways intercommunicate preselected two web-threading guideways that are adjacent each other circumferentially of the rotary switch. Thus the rotary switch may be angularly displaced by the switch drive means between a position where the two diametrally opposed pairs of web-threading guideways are intercommunicated via the two rectilinear switching guideways, and at least one other position where two preselected circumferentially neighboring pairs of web-threading guideways are separately intercommunicated via the two arcuate switching guideways.
In one preferred embodiment of the invention the rotary switch moves between two positions; that is, there is only one other position than the first recited position. In this case the rotary switch is driven forty-five degrees between the two positions. A simple fluid-actuated cylinder, preferably in combination with adjustable limit stops, suffices for such angular motion of the rotary switch.
In another preferred embodiment the rotary switch is movable to two other positions from the first recited position, the two other positions being angularly displaced forty-five degrees in two opposite directions from the first position. Thus the two arcuate switching guideways in the rotary switch may intercommunicate the four web-threading guideways in any circumferentially neighboring pairs. The switch drive means in this case may comprise a tandem connection of two fluid-actuated cylinders.
Either way, the switch drive means can be far simpler in construction than that of the prior art multiway switching device which had to swivel the switch through ninety degrees for switching from one diametrally opposed pair of web-threading guideways to another, and a much less angle for switching from two pairs of circumferentially neighboring web-threading guideways to the other two pairs of such guideways. In contrast to the prior art, according to the invention, the rotary switch is required to turn a fixed angle of forty-five degrees only, so that only one or two fluid-actuated cylinders of standard construction are needed in combination with a simple motion translating mechanism such as a lever for driving the switch.
Preferably, the switch drive means may include a pair of adjustable abutments, such as threaded fastener elements, for limiting the angular displacement of the switch. The switch will then stop in the exact positions required for accurate web switching.
Despite the simplicity of the switch drive means, moreover, the switching guideways in the rotary switch are relatively simple in the shape. The rotary switch is therefore easy and inexpensive of manufacture. Although the switching guideways have intersections, all such intersections can be made at right angles, or nearly so, thereby precluding the likelihood of the web deviating from the desired guideway while being switched.
The above and other objects, features and advantages of the invention and the manner of realizing them will become more apparent, and the invention itself will best be understood, from the following description taken together with the attached drawings showing the preferred embodiments of the invention.